Air conditioning system, control device and control method

Abstract

To provide an air conditioning system, a control device and a control method capable of suppressing energy consumption.SOLUTION: An air conditioning system has a first indoor unit, a second indoor unit, a first control section and a second control section. The first indoor unit blows out temperature-controlled air from an upper part of a space to inside of the space. The second indoor unit blows out temperature-controlled air from an underfloor part of the space to inside of the space. When a temperature of the upper part of the space is defined as an upper temperature and the upper temperature as a target is defined as a target upper temperature, the first control section controls an operation of the first indoor unit so that the upper temperature comes close to the target upper temperature. When a temperature of the lower part of the space is defined as a lower temperature and the lower temperature as a target is defined as a target lower temperature, the second control section controls an operation of the second indoor unit so that the lower temperature comes close to the target lower temperature. When the space is heated, the second control section sets the target lower temperature to be lower than the target upper temperature.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an air conditioning system, a control device, and a control method. [Background technology]

[0002] An air conditioning system has been proposed that includes a first indoor unit and a second indoor unit. The first indoor unit blows temperature-controlled air into the interior of the space from above. The second indoor unit blows temperature-controlled air into the interior of the space from under the floor of the space. Air conditioning systems are required to reduce energy consumption. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3263324 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide an air conditioning system, a control device, and a control method that can reduce energy consumption. [Means for solving the problem]

[0005] The air conditioning system of a first aspect of the embodiment has a first indoor unit, a second indoor unit, a first control unit, and a second control unit. The first indoor unit blows temperature-adjusted air into the space from the upper part of the space. The second indoor unit blows temperature-adjusted air into the space from under the floor of the space. When the temperature in the upper part of the space is set as the upper temperature and the target upper temperature is set as the target upper temperature, the first control unit controls the operation of the first indoor unit so that the upper temperature approaches the target upper temperature. When the temperature in the lower part of the space is set as the lower temperature and the target lower temperature is set as the target lower temperature, the second control unit controls the operation of the second indoor unit so that the lower temperature approaches the target lower temperature. When heating the space, the second control unit sets the target lower temperature lower than the target upper temperature.

[0006] In a second aspect of the embodiment, in the air conditioning system according to the first aspect, the temperature outside the space is defined as the external temperature, and the difference between the target upper temperature and the target lower temperature is defined as the target temperature difference. The second control unit sets the target temperature difference when the external temperature is a first temperature to be smaller than the target temperature difference when the external temperature is a second temperature higher than the first temperature.

[0007] The air conditioning system of a third embodiment has a first indoor unit, a second indoor unit, a first control unit, and a second control unit. The first indoor unit blows temperature-adjusted air into the space from the upper part of the space. The second indoor unit blows temperature-adjusted air into the space from under the floor of the space. When the temperature in the upper part of the space is set as the upper temperature and the target upper temperature is set as the target upper temperature, the first control unit controls the operation of the first indoor unit so that the upper temperature approaches the target upper temperature. When the temperature in the lower part of the space is set as the lower temperature and the target lower temperature is set as the target lower temperature, the second control unit controls the operation of the second indoor unit so that the lower temperature approaches the target lower temperature. When cooling the space, the second control unit sets the target lower temperature higher than the target upper temperature.

[0008] In a fourth aspect of the embodiment, in the air conditioning system described in the third aspect, the second control unit instructs the second indoor unit to perform condensation prevention operation after the lower temperature falls below the target lower temperature, in which unadjusted air is blown from under the floor of the space into the interior of the space.

[0009] In a fifth aspect of the embodiment, in the air conditioning system described in the third aspect, the second control unit instructs the second indoor unit to perform condensation prevention operation, which sets the temperature of the air blown from under the floor of the space into the interior of the space to a temperature higher than the dew point temperature of the space. In a sixth aspect of the embodiment, in the air conditioning system according to the fourth or fifth aspect, the second control unit sets the dew condensation prevention operation time to half or less of the cooling operation time.

[0010] In embodiment aspect 7, in the air conditioning system described in any one of aspects 1 to 6, the capacity ratio of the rated output of the second indoor unit to the total value of the rated output of the first indoor unit and the rated output of the second indoor unit is 10% or more and 50% or less. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram for explaining an overview of air conditioning control by an air conditioning system according to an embodiment; [Figure 2] 1 is a graph showing the relationship between the partial load factor of a compressor and energy efficiency. [Figure 3] 1 is a block diagram showing the overall configuration of an air conditioning system according to an embodiment. [Figure 4] 4 is a flowchart showing the operation of the first indoor unit. [Figure 5] 6 is a flowchart showing the heating operation of the second indoor unit. [Figure 6] 6 is a graph showing the change over time in temperature and amount of heat processed when the air conditioning system of the comparative example performs heating operation. [Figure 7] 6 is a graph showing changes over time in temperature and amount of heat processed when the air conditioning system of the embodiment performs heating operation. [Figure 8] 6 is a flowchart showing the cooling operation of the second indoor unit. [Figure 9] 6 is a graph showing the change in temperature and amount of heat processed over time when the air conditioning system of the comparative example performs cooling operation. [Figure 10]6 is a graph showing changes in temperature and heat processing amount over time when the air conditioning system of the embodiment performs cooling operation. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an air conditioning system, a control device, and a control method according to an embodiment will be described with reference to the drawings.

[0013] FIG. 1 is a schematic diagram for explaining an overview of air conditioning control by an air conditioning system 1 in an embodiment. FIG. 1 shows a vertical cross-sectional view of a portion of a building including a space S. For example, the building is an office building, and the space S is an office. The air conditioning system 1 is a system that conditions the air in the space S. The air conditioning system 1 has a first indoor unit (ceiling-type indoor unit) 10, a second indoor unit (floor-type indoor unit) 20, an outdoor unit 30, and a remote control (remote controller) 25.

[0014] The first indoor unit 10 is an indoor unit of a ceiling-air-conditioning system. The first indoor unit 10 includes a heat exchanger, a blower, an expansion valve, etc. For example, the first indoor unit 10 is a ceiling cassette type four-way air-outlet indoor unit. The first indoor unit 10 blows temperature-controlled air into the space S from the ceiling above the space S. Multiple first indoor units 10 are installed at intervals on the ceiling of the space S.

[0015] The second indoor unit 20 is an indoor unit of an underfloor air conditioner. The second indoor unit 20 includes a heat exchanger, a blower, an expansion valve, etc. The second indoor unit 20 is installed above the ceiling of the space S. A vertical duct 40 is installed on the side wall of the space S. The space S has a double floor under the floor, which functions as an underfloor air supply chamber 45. A horizontal duct may be installed instead of the underfloor air supply chamber 45. A plurality of air outlets 50 are provided on the floor surface of the space S. Air discharged from the second indoor unit 20 passes through the vertical duct 40 and the underfloor air supply chamber 45, and is blown out into the space S from the plurality of air outlets 50. The second indoor unit 20 blows temperature-adjusted air from under the floor of the space S into the interior of the space S.

[0016] The outdoor unit 30 is installed outside the building. The outdoor unit 30 includes a compressor, a four-way valve, a heat exchanger, etc. A plurality of first indoor units 10 and second indoor units 20 are connected in parallel to the outdoor unit 30 via refrigerant piping 35 to form a refrigeration cycle device. The air conditioning system 1 is a multi-type air conditioning system.

[0017] The air conditioning system 1 has a floor-air-supply air conditioner in addition to a ceiling-supply air conditioner. This reduces the temperature difference between the top and bottom of the space S. The feet are warmed, increasing comfort. The set temperature can be reduced, reducing energy consumption.

[0018] The capacity ratio of the second indoor unit 20 in the air conditioning system 1 will be explained. Fig. 2 is a graph showing the relationship between the partial load factor of a compressor and energy efficiency. The partial load factor of a compressor is the output ratio to the rated output. Energy efficiency is the coefficient of performance (COP) of the refrigeration cycle. As shown in Fig. 2, when the partial load factor of the compressor is 25 to 60% (output ratio is 0.25 to 0.6), the energy efficiency of the refrigeration cycle increases.

[0019] The first indoor unit 10 is usually selected to have a high horsepower relative to the area to be air-conditioned. This is to avoid insufficient cooling capacity even on extremely hot days. When a first indoor unit 10 with a high horsepower is installed, the compressor is likely to operate at a low partial load rate. For example, the operating time will be longer when the partial load rate is 10% or less, and shorter when the partial load rate is 25% to 60%. Furthermore, because the first indoor unit 10 primarily uses convection for air conditioning, it takes a short time to reach the target temperature. If the first indoor unit 10 repeatedly starts and stops near the target temperature, the compressor will operate intermittently. Intermittent operation of the compressor is undesirable from an energy-saving perspective.

[0020] On the other hand, in the second indoor unit 20, the compressor is likely to operate at a partial load factor of 25 to 60%. However, in the second indoor unit 20, a large amount of heat is absorbed by the building structure, such as the underfloor slab, so it takes a long time to reach the target temperature. As a result, the compressor may operate at a partial load factor of 90% or more, which cannot be said to be highly efficient.

[0021] For this reason, it is desirable to use the first indoor unit 10 and the second indoor unit 20 in combination. Furthermore, it is desirable to set the capacity ratio of the second indoor unit 20 to the total capacity of the outdoor unit 30 to be between 10% and 50%. For example, the rated output of multiple first indoor units 10 is 12 horsepower, and the rated output of multiple second indoor units 20 is 4 horsepower. The total rated output of both units is 16 horsepower, and the rated output of the second indoor unit 20, 4 horsepower, is a capacity ratio of 25%.

[0022] By setting the capacity ratio of the second indoor unit 20 to 10% or more, it is possible to suppress intermittent operation of the compressor with a partial load rate of less than 25%. By setting the capacity ratio of the second indoor unit 20 to 50% or less, it is possible to suppress high-load operation of the compressor with a partial load rate of more than 60%. Therefore, by setting the capacity ratio of the second indoor unit 20 to be between 10% and 50%, it is possible to suppress energy consumption.

[0023] Returning to FIG. 1, the air conditioning system 1 has a lower temperature sensor 21, a blowout temperature sensor 22, and an external temperature sensor 31. The lower temperature sensor (remote thermosensor) 21 measures the temperature (lower temperature) at the lower part of the space S. For example, the lower temperature sensor 21 is installed at a height of 30 cm above the floor. The lower temperature sensor 21 outputs a signal (lower temperature signal) corresponding to the lower temperature. The air conditioning system 1 may have a radiant temperature sensor instead of the lower temperature sensor 21. The radiant temperature sensor is installed on the ceiling surface or the like and measures the radiant temperature of the floor surface.

[0024] The blowout temperature sensor 22 measures the temperature (blowout temperature) of the air blown out from the outlet 50. The blowout temperature sensor 22 outputs a signal (blowout temperature signal) corresponding to the blowout temperature. The external temperature sensor 31 measures the temperature (external temperature) outside the space S. The external temperature sensor 31 outputs a signal (external temperature signal) corresponding to the external temperature.

[0025] FIG. 3 is a block diagram showing the overall configuration of an air conditioning system 1 according to the embodiment. The remote control 25 is an input interface that accepts inputs related to user instructions for the air conditioning system 1. The remote control 25 accepts inputs related to instructions (operation instructions) to start and stop operation of the air conditioning system 1. The remote control 25 outputs a signal (operation instruction signal) corresponding to the operation instruction. The remote control 25 accepts inputs related to instructions for the set temperature of the space S. The remote control 25 outputs a signal (set temperature signal) corresponding to the set temperature to the first indoor unit 10 and the second indoor unit 20.

[0026] The first indoor unit 10 has an intake temperature sensor 11, an intake humidity sensor 12, and a first control unit 13. The suction temperature sensor 11 measures the temperature (suction temperature) of air sucked into the first indoor unit 10 from the space S. The suction temperature corresponds to the temperature at the top of the space S (top temperature). The suction temperature sensor 11 outputs a signal (suction temperature signal) corresponding to the suction temperature. The intake humidity sensor 12 measures the humidity (intake humidity) of the air that is drawn into the first indoor unit 10 from the space S. The intake humidity sensor 12 outputs a signal (intake humidity signal) corresponding to the intake humidity.

[0027] The first control unit 13 receives a set temperature signal from the remote control 25. The first control unit 13 receives a suction temperature signal from the suction temperature sensor 11. The first control unit 13 controls the operation of the first indoor unit 10 based on the set temperature and the suction temperature. The operation of the multiple first indoor units 10 is controlled individually by each first control unit 13.

[0028] As shown in FIG. 3, the second indoor unit 20 has a second control section (control section, control device) 23. The second control unit 23 receives a set temperature signal from the remote control 25. The second control unit 23 receives a lower temperature signal from the lower temperature sensor 21, an external temperature signal from the external temperature sensor 31, an intake humidity signal from the intake humidity sensor 12, and a blow-out temperature signal from the blow-out temperature sensor 22. The second control unit 23 controls the operation of the second indoor unit 20 based on the set temperature, the lower temperature, the external temperature, the intake humidity, and the blow-out temperature.

[0029] The first control unit 13 and the second control unit 23 may be provided separately from the first indoor unit 10 and the second indoor unit 20, for example, as controllers for cooperative control of the first indoor unit 10 and the second indoor unit 20. They may also be provided in the outdoor unit 30. Furthermore, the outdoor unit 30 may be configured to have a separate control unit. In other words, the first control unit 13 and the second control unit 23 may be configured to issue control instructions to the first indoor unit 10 and the second indoor unit 20. Furthermore, the first control unit 13 and the second control unit 23 may communicate with each other, or may communicate via another control unit. Furthermore, the various sensors may directly transmit and receive signals to and from the first control unit 13 and the second control unit 23, or may do so indirectly via other control units.

[0030] The control units such as the first control unit 13 and the second control unit 23 each include, for example, a processor such as a CPU (Central Processing Unit), a memory, and an auxiliary storage device connected via a bus. The control units such as the first control unit 13 and the second control unit 23 read and execute programs from, for example, the auxiliary storage device. The auxiliary storage device is configured using a storage medium such as a magnetic hard disk drive or a semiconductor storage device. For example, the auxiliary storage device is configured using a non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory).

[0031] All or part of the control units such as the first control unit 13 and the second control unit 23 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The program may be transmitted via a telecommunications line.

[0032] A control method for the air conditioning system 1 will now be described. First, a description will be given of a case where the air conditioning system 1 performs heating operation. Specific examples of temperatures may be shown in parentheses below.

[0033] First, the operation of the first indoor unit 10 will be described. FIG. 4 is a flowchart showing the operation of the first indoor unit 10. The first control section 13 of the first indoor unit 10 acquires the set temperature (S12). Specifically, the first control unit 13 receives a set temperature signal from the remote control 25. The first control unit 13 obtains the set temperature (23° C.) from the set temperature signal.

[0034] The first control unit 13 calculates the target upper portion temperature TS1 (S14). The target upper temperature TS1 is a target value for the upper temperature of the space S. Due to the influence of rising warm air, the upper temperature of the space S becomes higher than the temperature (intermediate temperature) in the middle part of the space S in the vertical direction. The target upper temperature TS1 is a temperature obtained by adding a correction value 1a to the set temperature (23°C). The correction value 1a is set, for example, according to how easily the space S warms up. For example, in the case of heating operation, the correction value 1a is 1°C, and the target upper temperature TS1 is 24°C. The first control unit 13 outputs a signal (target upper temperature signal) corresponding to the target upper temperature TS1 to the second control unit 23.

[0035] The first control unit 13 acquires the suction temperature T1 (S16). Specifically, the first control unit 13 receives a suction temperature signal from the suction temperature sensor 11 and acquires the suction temperature T1. The first control units 13 of the multiple first indoor units 10 receive the suction temperature signals from their respective suction temperature sensors 11 and acquire their respective suction temperatures T1. For example, the first control unit 13 acquires 18°C ​​as the suction temperature T1.

[0036] The first control unit 13 performs normal temperature control (S18). Specifically, the first control unit 13 controls the operation of the first indoor unit 10 based on the difference between the target upper temperature TS1 (24°C) and the suction temperature T1 (18°C).

[0037] A specific example of normal temperature control is as follows. A table related to the aperture of the expansion valve provided in the first indoor unit 10 is recorded in the auxiliary storage device of the first control unit 13. The table records the aperture of the expansion valve corresponding to the difference between the target top temperature TS1 (24°C) and the suction temperature T1 (18°C). The first control unit 13 references the table and determines the aperture of the expansion valve from the difference between the target top temperature TS1 and the suction temperature T1. The first control unit 13 adjusts the aperture of the expansion valve of the first indoor unit 10 based on the determined aperture of the expansion valve, and controls the operation of the first indoor unit 10. The first control unit 13 may control the operation of the first indoor unit 10 by adjusting the air volume of a blower provided in the first indoor unit 10, instead of or in addition to adjusting the aperture of the expansion valve.

[0038] Normal temperature control causes suction temperature T1 (18°C) to approach target upper temperature TS1 (24°C). When suction temperature T1 exceeds target upper temperature TS1, first control unit 13 temporarily suspends operation of first indoor unit 10. Thereafter, when suction temperature T1 falls below target upper temperature TS1 (or a temperature slightly lower than target upper temperature TS1), first control unit 13 resumes operation of first indoor unit 10.

[0039] The first control section 13 determines whether or not it is necessary to terminate the operation of the first indoor unit 10 (S20). Specifically, the first control unit 13 receives an operation instruction signal from the remote control 25 and acquires an operation instruction for the air conditioning system 1. If the first control unit 13 has not acquired an instruction to end operation (determination in S20 is No), it repeats the processing from S16 onwards. If the first control unit 13 has acquired an instruction to end operation (determination in S20 is Yes), it ends the operation of the first indoor unit 10.

[0040] Next, the operation of the second indoor unit 20 will be described. FIG. 5 is a flowchart showing the heating operation of the second indoor unit 20. The second control section 23 of the second indoor unit 20 acquires the set temperature (S42). Specifically, second control unit 23 receives a set temperature signal from remote control 25. Second control unit 23 obtains the set temperature (23° C.) from the set temperature signal.

[0041] The second control unit 23 calculates the target lower temperature TS2 (S44). The target lower temperature TS2 is a target value for the lower temperature of the space S. When heating the space S, the second control unit 23 sets the target lower temperature TS2 lower than the target upper temperature TS1. The second control unit 23 sets the target lower temperature TS2 by subtracting the adjustment value 2a from the set temperature (23°C). The second control unit 23 receives a target upper temperature signal from the first control unit 13 and acquires the target upper temperature TS1. The second control unit 23 sets the adjustment value 2a so that the target lower temperature TS2 is lower than the target upper temperature TS1. For example, the adjustment value 2a is 1°C, and the target lower temperature TS2 is 22°C. The target lower temperature TS2 of 22°C is lower than the target upper temperature TS1 of 24°C.

[0042] The second control unit 23 acquires the lower temperature T2 (S46). Specifically, the second control unit 23 receives a lower temperature signal from the lower temperature sensor 21 and acquires the lower temperature T2. For example, the second control unit 23 acquires 18°C ​​as the lower temperature T2.

[0043] The second control unit 23 performs normal temperature control (S50). Specifically, the second control section 23 controls the operation of the second indoor unit 20 based on the difference between the target lower temperature TS2 (22°C) and the lower temperature T2 (18°C).

[0044] A specific example of normal temperature control is as follows. A table related to the output of the expansion valve provided in the second indoor unit 20 is recorded in the auxiliary storage device of the second control unit 23. The table records the expansion valve aperture corresponding to the difference between the target lower temperature TS2 (22°C) and the lower temperature T2 (18°C). The second control unit 23 references the table and determines the expansion valve aperture from the difference between the target lower temperature TS2 and the lower temperature T2. The second control unit 23 adjusts the expansion valve aperture of the second indoor unit 20 based on the determined expansion valve aperture, and controls the operation of the second indoor unit 20. The second control unit 23 may control the operation of the second indoor unit 20 by adjusting the airflow rate of a blower provided in the second indoor unit 20, instead of or in addition to adjusting the expansion valve aperture.

[0045] Normal temperature control causes the lower temperature T2 (18°C) to approach the target lower temperature TS2 (22°C). When the lower temperature T2 exceeds the target lower temperature TS2, the second control unit 23 temporarily suspends operation of the second indoor unit 20. Thereafter, when the lower temperature T2 falls below the target lower temperature TS2 (or a temperature slightly lower than the target lower temperature TS2), the second control unit 23 resumes operation of the second indoor unit 20.

[0046] The second control section 23 determines whether or not it is necessary to terminate the operation of the second indoor unit 20 (S52). Specifically, the second control unit 23 receives an operation instruction signal from the remote control 25 and acquires an operation instruction for the air conditioning system 1. If the second control unit 23 has not acquired an instruction to end operation (determination in S52 is No), it repeats the processing from S46 onwards. If the second control unit 23 has acquired an instruction to end operation (determination in S52 is Yes), it ends the operation of the second indoor unit 20.

[0047] The air conditioning system 1 heats the space S in the above manner. Immediately after the air conditioning system 1 starts operating, both the first indoor unit 10 and the second indoor unit 20 are operated. This causes the temperature of the space S to rise quickly. In particular, the operation of the second indoor unit 20 heats the lower part of the space S where the user is present.

[0048] As described above, the air discharged from the second indoor unit 20 (discharge air) passes through the vertical duct 40 and the underfloor air supply chamber 45, and is blown out into the space S from the outlet 50. When the discharge air passes through the underfloor air supply chamber 45, part of the heat of the discharge air is absorbed by the underfloor slab. If the insulation performance of the underfloor slab is low, much of the heat of the discharge air will be absorbed by the underfloor slab and will not be used to heat the space S. This increases the energy consumption of the air conditioning system 1.

[0049] Fig. 6 is a graph showing the time changes in temperature and amount of heat processed when the air conditioning system of the comparative example is performing heating operation. The upper graph in Fig. 6 is a graph showing the time changes in upper temperature (suction temperature) and lower temperature in the comparative example. The lower graph in Fig. 6 is a graph showing the time changes in amount of heat processed by the first indoor unit and the second indoor unit of the comparative example.

[0050] In the comparative example, the target lower temperature is set to the same temperature (24°C) as the target upper temperature. As shown in the upper diagram of Figure 6, the second indoor unit of the comparative example aims for the target lower temperature (24°C), and the lower temperature rises above the set temperature (23°C). However, as mentioned above, the heat of the air discharged from the second indoor unit is absorbed, for example, by the slab under the floor, and operation may continue without reaching the target lower temperature (24°C). Therefore, as shown in the lower diagram of Figure 6, the second indoor unit of the comparative example continues to process the heat (heating operation). This increases the energy consumption of the air conditioning system of the comparative example.

[0051] Fig. 7 is a graph showing the change over time in temperature and amount of heat processed when the air conditioning system 1 of the embodiment is performing heating operation. The upper graph in Fig. 7 is a graph showing the change over time in the upper temperature (suction temperature T1) and lower temperature T2 in the embodiment. The lower graph in Fig. 7 is a graph showing the change over time in the amount of heat processed by the first indoor unit 10 and the second indoor unit 20 of the embodiment.

[0052] As described above, the second control unit 23 of the second indoor unit 20 in this embodiment sets the target lower temperature TS2 lower than the target upper temperature TS1 when heating the space S. Therefore, as shown in the upper diagram of Fig. 7, the lower temperature T2 reaches the target lower temperature TS2 before the upper temperature (suction temperature T1) reaches the target upper temperature TS1. As a result, the second indoor unit 20 pauses before the first indoor unit 10, as shown in the lower diagram of Fig. 7.

[0053] By temporarily stopping the second indoor unit 20 first, the amount of heat absorbed by the underfloor slab decreases. Even if the second indoor unit 20 temporarily stops first, the temperature at the bottom of the space S is less likely to drop due to the heat storage effect of the underfloor slab. This makes it possible to reduce the energy consumption of the air conditioning system 1.

[0054] The setting of the target lower temperature TS2 based on the external temperature and the thermal insulation performance of the underfloor slab will now be described. When the temperature outside the space S (external temperature) is low, the heat inside the space S is likely to escape to the outside. In this case, the difference (temperature unevenness) between the upper and lower temperatures of the space S becomes large. Therefore, the second control unit 23 may set the target lower temperature TS2 based on the external temperature.

[0055] Specifically, the second control unit 23 receives an external temperature signal from the external temperature sensor 31 and acquires the external temperature. A table containing a correspondence between the external temperature and the adjustment value 2a is recorded in the auxiliary storage device of the second control unit 23. In the table, the adjustment value 2a when the external temperature is a first temperature is set to be smaller than the adjustment value 2a when the external temperature is a second temperature higher than the first temperature. The second control unit 23 refers to the table and finds the adjustment value 2a corresponding to the acquired external temperature. The second control unit 23 subtracts the adjustment value 2a from the set temperature to set the target lower temperature TS2. The difference between the target upper temperature TS1 and the target lower temperature TS2 is the target temperature difference. The target temperature difference when the external temperature is the first temperature is set to be smaller than the target temperature difference when the external temperature is the second temperature. This suppresses temperature unevenness in the space S.

[0056] Furthermore, if the insulation performance of the underfloor slab is low, the heat of the air discharged from the second indoor unit 20 is likely to be absorbed by the underfloor slab. In this case, temperature unevenness in the space S will also increase. Therefore, the target lower temperature TS2 may be set based on the insulation performance of the underfloor slab. For example, the insulation performance of the underfloor slab is evaluated by the thickness of the insulation material. The adjustment value 2a when the insulation material has a first thickness is set smaller than the adjustment value 2a when the insulation material has a second thickness that is thicker than the first thickness. The target temperature difference when the insulation material has the first thickness is set smaller than the target temperature difference when the insulation material has the second thickness. This suppresses temperature unevenness in the space S.

[0057] Next, a case where the air conditioning system 1 performs cooling operation will be described. First, the operation of the first indoor unit 10 will be described with reference to FIG. The first control unit 13 acquires the set temperature (25° C.) (S12).

[0058] The first control unit 13 calculates the target upper temperature TS1 (S14). The target upper temperature TS1 is a temperature obtained by adding a correction value 1a to the set temperature (25°C). For example, in the case of cooling operation, the correction value 1a is 0°C, and the target upper temperature TS1 is 25°C.

[0059] The first control unit 13 acquires the suction temperature T1 (30° C.) (S16). The first control unit 13 performs normal temperature control (S18). Normal temperature control causes the suction temperature T1 (30°C) to approach the target upper temperature TS1 (25°C). When the suction temperature T1 falls below the target upper temperature TS1, the first control unit 13 temporarily suspends operation of the first indoor unit 10. Thereafter, when the suction temperature T1 exceeds the target upper temperature TS1 (or a temperature slightly higher than the target upper temperature TS1), the first control unit 13 resumes operation of the first indoor unit 10.

[0060] The first control unit 13 judges (S20) whether or not it is necessary to terminate the operation of the first indoor unit 10. When the first control unit 13 acquires an instruction to terminate operation (the judgment in S20 is Yes), it terminates the operation of the first indoor unit 10.

[0061] Next, the operation of the second indoor unit 20 will be described. FIG. 8 is a flowchart showing the cooling operation of the second indoor unit 20. The second control section 23 of the second indoor unit 20 acquires the set temperature (25°C) (S62).

[0062] The second control unit 23 calculates a target lower temperature (target lower temperature) TS2 (S64). When cooling the space S, the second control unit 23 sets the target lower temperature TS2 higher than the target upper temperature TS1. The second control unit 23 sets the target lower temperature TS2 by adding an adjustment value 2a to the set temperature (25°C). The second control unit 23 receives a target upper temperature signal from the first control unit 13 and acquires the target upper temperature TS1. The second control unit 23 sets the adjustment value 2a so that the target lower temperature TS2 is higher than the target upper temperature TS1. For example, the adjustment value 2a is 1°C, and the target lower temperature TS2 is 26°C. The target lower temperature TS2 of 26°C is higher than the target upper temperature TS1 of 25°C.

[0063] The second control unit 23 acquires the lower temperature T2 (S66). The second control unit 23 performs normal temperature control (S70). Through normal temperature control, the lower temperature T2 (30°C) approaches the target lower temperature TS2 (26°C). When the lower temperature T2 falls below the target lower temperature TS2, the second control unit 23 temporarily suspends operation of the second indoor unit 20. Thereafter, when the lower temperature T2 exceeds the target lower temperature TS2 (or a temperature slightly higher than the target lower temperature TS2), the second control unit 23 resumes operation of the second indoor unit 20. The second control unit 23 performs the dew condensation prevention operation (S71). The dew condensation prevention operation will be described in detail later.

[0064] The second control unit 23 determines whether or not it is necessary to terminate the operation of the second indoor unit 20 (S72). When the second control unit 23 acquires an instruction to terminate operation (the determination in S52 is Yes), it terminates the operation of the second indoor unit 20.

[0065] The air conditioning system 1 cools the space S in the above manner. Immediately after the air conditioning system 1 starts operating, both the first indoor unit 10 and the second indoor unit 20 are operated. This causes the temperature of the space S to drop quickly. In particular, the operation of the second indoor unit 20 cools the lower part of the space S where the user is present.

[0066] As described above, the air discharged from the second indoor unit 20 (discharge air) passes through the vertical duct 40 and the underfloor air supply chamber 45, and is blown out from the outlet 50 into the space S. When the air passes through the underfloor air supply chamber 45, the underfloor slab is cooled. Some of the air inside the space S may flow into the underfloor air supply chamber 45 through the outlet 50. If the humidity (dew point temperature) of this air is high, condensation may occur on the underfloor slab side of the underfloor air supply chamber 45.

[0067] Fig. 9 is a graph showing the change in temperature and amount of heat processed over time when the air conditioning system of the comparative example is in cooling operation. The upper graph in Fig. 9 is a graph showing the change in upper temperature (suction temperature) and lower temperature over time in the comparative example. The lower graph in Fig. 9 is a graph showing the change in amount of heat processed over time in the first indoor unit and the second indoor unit of the comparative example.

[0068] In the comparative example, the target lower temperature is set to the same temperature (25°C) as the target upper temperature. As shown in the upper diagram of FIG. 9, the second indoor unit of the comparative example aims for the target lower temperature (25°C) and the lower temperature drops to close to the target lower temperature (25°C). However, as mentioned above, the air discharged from the second indoor unit of the comparative example cools, for example, the underfloor slab, so operation may continue without reaching the target lower temperature (25°C). Therefore, as shown in the lower diagram of FIG. 9, the second indoor unit of the comparative example continues to process heat (cooling operation). This increases the energy consumption of the air conditioning system of the comparative example. Furthermore, the underfloor slab may be overcooled, increasing the possibility of condensation forming in the underfloor air supply chamber 45.

[0069] Fig. 10 is a graph showing the change in temperature and amount of heat processed over time when the air conditioning system 1 of the embodiment is performing cooling operation. The upper graph in Fig. 10 is a graph showing the change in upper temperature (suction temperature T1) and lower temperature T2 over time in the embodiment. The lower graph in Fig. 10 is a graph showing the change in amount of heat processed over time in the first indoor unit 10 and the second indoor unit 20 of the embodiment.

[0070] As described above, the second control unit 23 of the second indoor unit 20 in this embodiment sets the target lower temperature TS2 higher than the target upper temperature TS1 when cooling the space S. Therefore, as shown in the upper diagram of Figure 10, the lower temperature T2 reaches the target lower temperature TS2 before the upper temperature (suction temperature T1) reaches the target upper temperature TS1. As a result, the second indoor unit 20 pauses before the first indoor unit 10.

[0071] By temporarily stopping the second indoor unit 20 first, excessive cooling of the underfloor slab is suppressed. This reduces the possibility of condensation forming in the underfloor air supply chamber 45. Even if the second indoor unit 20 temporarily stops first, the cool air blown out from the first indoor unit 10 descends, so the temperature at the bottom of the space S is less likely to rise. This makes it possible to suppress the energy consumption of the air conditioning system 1.

[0072] The dew condensation prevention operation of the second indoor unit 20 will be described. As described above, the second indoor unit 20 has a heat exchanger. When the second indoor unit 20 performs cooling operation, the heat exchanger functions as a heat absorber (evaporator). As a result, condensation occurs in the heat exchanger. When the lower temperature falls below the target lower temperature TS2, the second indoor unit 20 temporarily stops. This causes the condensation in the heat exchanger to evaporate, and the humidity (dew point temperature) of the air in the vertical duct 40 and the underfloor air supply chamber 45 increases. Because the second indoor unit 20 was performing cooling operation, the temperature on the underfloor slab side of the underfloor air supply chamber 45 has decreased. If air with a high dew point temperature remains in the underfloor air supply chamber 45, condensation may occur in the underfloor air supply chamber 45.

[0073] The second control unit 23 of the second indoor unit 20 performs condensation prevention operation after the lower temperature falls below the target lower temperature TS2 (S71). As the condensation prevention operation, the second control unit 23 controls the operation of the second indoor unit 20 so that untemperature-adjusted air is blown from under the floor of the space S into the interior of the space S. Specifically, the second control unit 23 operates the fan for the heat exchanger of the second indoor unit 20 without operating the compressor of the outdoor unit 30. This allows air to circulate between the interior of the space S and the vertical duct 40 and the underfloor air supply chamber 45 without heat exchange in the heat exchanger. As a result, high-humidity air is less likely to remain in the underfloor air supply chamber 45. Furthermore, because air not temperature-adjusted in the heat exchanger flows through the underfloor air supply chamber 45, the temperature of the underfloor slab rises. This prevents condensation in the underfloor air supply chamber 45.

[0074] The second control unit 23 sets the duration of the anti-condensation operation (air blowing operation time) to less than half the duration of the cooling operation (cooling operation time). The amount of condensation water generated in the heat exchanger of the second indoor unit 20 increases in proportion to the cooling operation time. Therefore, the anti-condensation operation time is increased in proportion to the cooling operation time. This promotes evaporation of the condensation water in the heat exchanger and suppresses the accumulation of high-humidity air in the underfloor air supply chamber 45. However, experiments by the inventors have shown that the heat exchanger becomes dry before the anti-condensation operation time reaches half the cooling operation time. Therefore, by setting the anti-condensation operation time to less than half the cooling operation time, condensation in the underfloor air supply chamber 45 can be suppressed. Furthermore, because the anti-condensation operation time is shortened, energy consumption can be reduced.

[0075] The second control unit 23 may perform condensation prevention operation of the second indoor unit 20 based on the dew-point temperature and blow-out temperature of the space S. Specifically, the second control unit 23 receives an intake humidity signal from the intake humidity sensor 12 and acquires the intake humidity. The second control unit 23 calculates the dew-point temperature of the space S based on the intake humidity and the lower temperature. The second control unit 23 receives a blow-out temperature signal from the blow-out temperature sensor 22 and acquires the blow-out temperature. If the blow-out temperature is lower than the dew-point temperature of the space S, condensation is likely to occur in the under-floor air supply chamber 45. Therefore, when the blow-out temperature falls below the dew-point temperature of the space S, the second control unit 23 temporarily suspends the cooling operation of the second indoor unit 20 and performs condensation prevention operation. This increases the blow-out temperature, thereby effectively suppressing condensation in the under-floor air supply chamber 45.

[0076] The second control unit 23 may perform a cooling operation that increases the blow-out temperature as the condensation prevention operation. Specifically, the second control unit 23 performs the cooling operation by increasing the target lower temperature TS2. For example, the second control unit 23 increases the adjustment value 2a that is added to the set temperature (25°C) to increase the target lower temperature TS2. By performing a cooling operation that increases the blow-out temperature, condensation in the underfloor air supply chamber 45 can be suppressed.

[0077] A portion of the air conditioning system 1 in the above-described embodiment may be implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. The term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over a network such as the Internet or a telephone line, or media that store programs for a fixed period of time, such as volatile memory within a computer system serving as a server or client. The program may be a program that implements some of the above-described functions, or may be a program that can be implemented in combination with a program already stored in the computer system. The program may also be implemented using hardware such as a programmable logic device (PLD) or field programmable gate array (FPGA).

[0078] Furthermore, in the air conditioning system 1 of the above-described embodiment, the normal temperature control of the first indoor unit 10 and the second indoor unit 20 is performed by adjusting the opening of the expansion valves provided in each indoor unit and adjusting the airflow rate of the blower, but this is not limited to this. For example, the operation of the first indoor unit 10 and the second indoor unit 20 may be controlled based on the output of the compressor provided in the outdoor unit 30 in cooperation with an outdoor unit control unit provided in the outdoor unit 30. When the operation of the first indoor unit 10 and the second indoor unit 20 is controlled based on the output of the compressor, a table related to the output of the compressor provided in the outdoor unit 30 is recorded in the auxiliary storage device of the outdoor unit control unit. The table records the compressor output corresponding to the difference between the target upper temperature TS1 and the suction temperature T1 of the first indoor unit 10, and the compressor output corresponding to the difference between the target lower temperature TS2 and the lower temperature T2 of the second indoor unit 20. The outdoor unit control unit refers to the table and determines the compressor output from the difference between the target upper temperature TS1 and the suction temperature T1 of the first indoor unit 10, and the difference between the target lower temperature TS2 and the lower temperature T2 of the second indoor unit 20. The outdoor unit control unit drives the compressor based on the determined compressor output, and controls the operation of the first indoor unit 10 and the second indoor unit 20.

[0079] According to at least one of the embodiments described above, the second control unit 23 is provided, which sets the target lower temperature TS2 lower than the target upper temperature TS1 when heating the space S, and sets the target lower temperature TS2 higher than the target upper temperature TS1 when cooling the space S. This makes it possible to reduce energy consumption.

[0080] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0081] S...space, T1...suction temperature (upper temperature), T2...lower temperature, TS1...target upper temperature, TS2...target lower temperature, 1...air conditioning system, 10...first indoor unit, 13...first control unit, 20...second indoor unit, 23...second control unit.

Claims

1. a first indoor unit that blows temperature-adjusted air into the space from an upper portion of the space; a second indoor unit that blows temperature-adjusted air into the space from under the floor of the space; a first control unit that controls the operation of the first indoor unit so that the upper temperature approaches the target upper temperature when the temperature at the upper part of the space is defined as an upper temperature and the target upper temperature is defined as a target upper temperature; a second control unit that controls the operation of the second indoor unit so that the lower temperature approaches the target lower temperature when the temperature at the lower part of the space is defined as a lower temperature and the target lower temperature is defined as a target lower temperature, The second control unit sets the target lower temperature lower than the target upper temperature when heating the space. Air conditioning system.

2. When the temperature outside the space is defined as the external temperature and the difference between the target upper temperature and the target lower temperature is defined as the target temperature difference, the second control unit sets the target temperature difference when the external temperature is a first temperature to be smaller than the target temperature difference when the external temperature is a second temperature higher than the first temperature; The air conditioning system of claim 1 .

3. a first indoor unit that blows temperature-adjusted air into the space from an upper portion of the space; a second indoor unit that blows temperature-adjusted air into the space from under the floor of the space; a first control unit that controls the operation of the first indoor unit so that the upper temperature approaches the target upper temperature when the temperature at the upper part of the space is defined as an upper temperature and the target upper temperature is defined as a target upper temperature; a second control unit that controls the operation of the second indoor unit so that the lower temperature approaches the target lower temperature when the temperature at the lower part of the space is defined as a lower temperature and the target lower temperature is defined as a target lower temperature, The second control unit sets the target lower temperature higher than the target upper temperature when cooling the space. Air conditioning system.

4. the second control unit instructs the second indoor unit to perform a condensation prevention operation in which, after the lower temperature falls below the target lower temperature, unadjusted air is blown from under the floor of the space into the interior of the space. The air conditioning system according to claim 3 .

5. The second control unit instructs the second indoor unit to perform a condensation prevention operation in which a temperature of air blown out from under the floor of the space into the space is set higher than a dew point temperature of the space. The air conditioning system according to claim 3 .

6. The second control unit sets the dew condensation prevention operation time to half or less of the cooling operation time.

6. The air conditioning system according to claim 4 or 5.

7. a capacity ratio of the rated output of the second indoor unit to the total value of the rated output of the first indoor unit and the rated output of the second indoor unit is 10% or more and 50% or less; The air conditioning system according to claim 1 or 3.

8. A control device for an air conditioning system having a first indoor unit that blows temperature-adjusted air into the interior of a space from an upper portion of the space, and a second indoor unit that blows temperature-adjusted air into the interior of the space from under the floor of the space, When the temperature at the upper part of the space is defined as an upper temperature and the target upper temperature is defined as a target upper temperature, the operation of the first indoor unit is controlled so that the upper temperature approaches the target upper temperature; When the temperature at the lower part of the space is defined as a lower part temperature and the target lower part temperature is defined as a target lower part temperature, the operation of the second indoor unit is controlled so that the lower part temperature approaches the target lower part temperature; When heating the space, the target lower temperature is set lower than the target upper temperature; When cooling the space, the target lower temperature is set higher than the target upper temperature. Control device.

9. A control method for an air conditioning system having a first indoor unit that blows temperature-adjusted air into an interior of a space from an upper portion of the space, and a second indoor unit that blows temperature-adjusted air into the interior of the space from under a floor of the space, a step of controlling the operation of the first indoor unit so that the upper temperature approaches the target upper temperature when the temperature at the upper part of the space is defined as an upper temperature and the target upper temperature is defined as a target upper temperature; a step of controlling the operation of the second indoor unit so that the lower temperature approaches the target lower temperature when the temperature at the lower part of the space is defined as a lower temperature and the target lower temperature is defined as a target lower temperature; When heating the space, setting the target lower temperature lower than the target upper temperature; and setting the target lower temperature higher than the target upper temperature when cooling the space. Control method.

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